Patent Document 1 describes an electronic device such as a mobile phone that delivers an air conduction sound and a bone conduction sound to a user. Patent Document 1 also describes that the air conduction sound is a sound that is delivered to the auditory nerve of the user when vibration of the air caused by vibration of an object reaches the eardrum through the ear canal and vibrates the eardrum. Patent Document 1 further describes that the human body vibration sound is a sound that is delivered to the auditory nerve of the user via a part of a user's body (for example, the cartilage of the ear) in contact with an object being vibrating.
In the phone described in Patent Document 1, a vibrator in the form of a short rectangular plate made of a piezoelectric bimorph and a flexible material is attached to an outer surface of a housing via an elastic member. Patent Document 1 also describes that, upon application of a voltage on the piezoelectric bimorph of the vibrator, a piezoelectric material stretches in a longitudinal direction causing bending vibration of the vibrator and thus, when the user brings the vibrator into contact with the auricle, the air conduction sound and the human body vibration sound are delivered to the user.